docs: def Reynolds_factor(FL, C, d, Rev, full_trim=True):
      r'''Calculates the Reynolds number factor `FR` for a valve with a Reynolds
      number `Rev`, diameter `d`, flow coefficient `C`, liquid pressure recovery
      factor `FL`, and with either full or reduced trim, all according to
      IEC 60534 calculations.
  
  
      If full trim:
  
      .. math::
          F_{R,1a} = 1 + \left(\frac{0.33F_L^{0.5}}{n_1^{0.25}}\right)\log_{10}
          \left(\frac{Re_v}{10000}\right)
  
      .. math::
          F_{R,2} = \min(\frac{0.026}{F_L}\sqrt{n_1 Re_v},\; 1)
  
      .. math::
          n_1 = \frac{N_2}{\left(\frac{C}{d^2}\right)^2}
  
      .. math::
          F_R = F_{R,2} \text{ if Rev < 10 else } \min(F_{R,1a}, F_{R,2})
  
      Otherwise :
  
      .. math::
          F_{R,3a} = 1 + \left(\frac{0.33F_L^{0.5}}{n_2^{0.25}}\right)\log_{10}
          \left(\frac{Re_v}{10000}\right)
  
      .. math::
          F_{R,4} = \frac{0.026}{F_L}\sqrt{n_2 Re_v}
  
      .. math::
          n_2 = 1 + N_{32}\left(\frac{C}{d}\right)^{2/3}
  
      .. math::
          F_R = F_{R,4} \text{ if Rev < 10 else } \min(F_{R,3a}, F_{R,4})
  
      Parameters
      ----------
      FL : float
          Liquid pressure recovery factor of a control valve without attached
          fittings []
      C : float
          Metric Kv valve flow coefficient (flow rate of water at a pressure drop  
          of 1 bar) [m^3/hr]
      d : float
          Diameter of the valve [m]
      Rev : float
          Valve reynolds number [-]
      full_trim : bool
          Whether or not the valve has full trim
  
      Returns
      -------
      FR : float
          Reynolds number factor for laminar or transitional flow []
  
      Examples
      --------
      In Example 4, compressible flow with small flow trim sized for gas flow
      (Cv in the problem was converted to Kv here to make FR match with N32, N2):
  
      >>> Reynolds_factor(FL=0.98, C=0.015483, d=15., Rev=1202., full_trim=False)
      0.7148753122302025
  
  
      References
      ----------
      .. [1] IEC 60534-2-1 / ISA-75.01.01-2007
      '''
      if full_trim:
          n1 = N2/(min(C/d**2, 0.04))**2 # C/d**2 must not exceed 0.04
          FR_1a = 1 + (0.33*FL**0.5)/n1**0.25*log10(Rev/10000.)
          FR_2 = 0.026/FL*(n1*Rev)**0.5
          if Rev < 10:
              FR = FR_2
          else:
              FR = min(FR_2, FR_1a)
      else:
          n2 = 1 + N32*(C/d**2)**(2/3.)
          FR_3a = 1 + (0.33*FL**0.5)/n2**0.25*log10(Rev/10000.)
          FR_4 = min(0.026/FL*(n2*Rev)**0.5, 1)
          if Rev < 10:
              FR = FR_4
          else:
              FR = min(FR_3a, FR_4)
      return FR